Plastic is becoming more and more popular for use in all fields for its easy handling, non-reactivity, and other properties. One popular form of plastic is extrudate, which may be used in 3D printing, plastic welding, and so on. Despite demand, processed plastic like rod, wire, or filament is still relatively expensive compared to the raw materials. For example, 3D printing filament (e.g. processed plastic material) ranges from $20-50 per kilogram compared to $1-5 per kilogram of raw plastic pellets. Additionally, manufacturing and processing of the plastic material is almost always done in industrial-scale factories or sites, and the processed product then needs to be transported to the vendors and/or consumers, as such, lots of time, energy, and money are often spent on transportation alone.
Many processes involving plastic material (e.g. 3D printing/prototyping, shipping/packaging and so on) can result in large quantities of waste materials which must be re-transported and processed for recycling. Often, the quantity and/or quality of recycled plastic material is not worth the energy of separation, cleaning, and processing required by mass recirculation. This is an issue for the typical consumer as well as placing plastic waste in a recycling bin can be an inconvenience for the average consumer. These un-recycled plastics can end up in our parks, landfills and oceans and cause environmental damage in the long-run.
While industrial-scale grinders and extruders both exist, industrial extruders tend to rely on a very powerful drive motor to turn a feed auger, which forces and compresses raw plastic material down the extruder barrel to achieve melting largely through polymer shear (i.e., friction) heating. This method of melting takes a lot of torque delivered to the auger to overcome the frictional and compressive forces and can require a very powerful motor. This can in turn incur high power consumption/losses. Heat is then mainly removed using cooling fans and/or fluid to control heat distribution along the extruder's length. This method of melting can also require a high length to diameter ratio to ensure consistent melting, thus requiring such devices to be relatively large.
Another issue with existing extruders is that the auger configuration requires stringent and complex temperature control along portions of the auger so that the plastic material does not begin to melt and stick in the feeding area, which could obstruct the flow of the material in the feeding portion. In addition, most extruders typically are in continuous operation because shutting it down can cause the plastic material in the form of viscous liquid to cool down and solidify around the auger and lead to operational issues relating to re-starting the extruder.
Improvement is therefore desirable.